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How to make a Short Circuit Protection using 8 pin Relay

mrkel

Oct 13, 2019
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Hi. Im an electronics Engineering student. Going straight to the point we have this project which is a transistorized variable power supply. I manged to get my hands into a circuit that fits most of the requirements that our prof needs. Except for the short circuit protection which is also part of a led indicator if it on idle or on mode... I have looked everywhere and all I saw was for 5 pin relay. But We were required to use 8 pinned relay for our project. It would be very much appreciated if you guys could help me with this one. Feel free to ask more information about this problem of mine. Thank you very much in advance
 

Harald Kapp

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Nov 17, 2011
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I have looked everywhere and all I saw was for 5 pin relay.
Then you haven't looked everywhere.
Relays are normally not classified by their number of pins, but by their method of control (single coil, dual coil, AC, DC, latching, non-latching etc.) plus by their switch configuration (common ones being: single pole double pole, single throw, double throw, mostly combined in the form SPST, SPDT, DPST, DPDT, etc.).
A typical relay with 8 pins could have for example:
2 pins for the relay coil
6 pins for a dpdt contact configuration, meaning 2 sets of contacts, each with a common contact, a normally closed contact and a normally open contact .

How to use such a relay in your application depends on the control signals you have to control the coil side of the relay and on what you want or need to switch with the contact side.
A guess of mine: the control signal is derived from a current sense circuit (more specifically an overcurrent detector), the contact side is used to open the output circuit both on plus and minus to depatrate the load (aka short circuit) from the power supply.
But things may well be very different, depending on your circuit and details of the requirements specified by your prof.
 

Alec_t

Jul 7, 2015
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An electromechanical relay would likely operate too slowly to protect a transistorized power supply from a short-circuited output, although it could work if the output current became excessive over a relatively long period.
 
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